Extra Extra Money
Go to the workshop and hold [shift]+[alt] and press 5 to get $50,000.

50,000 credits
In the middle of a battle press ctrl and f4 and once the battle is done you will have 50,000 credits in your bank.(you must win the battle though and you have to be in the same ranking class as your opponent.

10,000 credits
To get 10,000 credits you must fight a bot called Guidera he is usually in england east, america east or america/england novice. He isn't controlled by a player battle him and lose 3 times, you must lose by falling off the edge. after 3 losses go to your workshop and you should have 10,000 credits. i have tried this 3 times and it's worked every time.